Grocery shopping seems like a harmless enough activity. It's a chore, but it's one that most of us do at least once a week, without giving much thought to what's going on behind the scenes at the supermarket.

How we shop has become a science that's studied endlessly. "Market researchers have worked for years to come up with ways to make sure shoppers see as many products as possible, because the more they see, the more they buy," says Marion Nestle, author of What to Eat: An Aisle-by-Aisle Guide to Savvy Food Choices and Good Eating.

So to make yourself a smarter shopper, learn about the top tricks and other secrets lurking at the supermarket.